Can't spawn at second elevator

[P'Titan Culé]

Hello,
My firend and I passed the office, unfortunatly he had to leave, so i passed the garage alone (with the valves and the skincrawnler). Then I passed the elevator and got the success "escape the darkrooms". We read that the elevators were checkpoints, so when I passed one I restarted the lobby so he can join me again. But then, the only option to spawn were "backroom lobby" so we have to do it all again and to be honnest we don't have the motivation...

Is there a way to get that elevator spawn ?
Is there a way to unlock all spawn so we can go to the last level we unlocked ?

Hope this question got to the right ears so we can have a solution...